The invention relates to a method for operating drive control units in a motor vehicle and to a motor vehicle.
Drive control units actuate different drives of the motor vehicle by outputting respective control signals. With respect to the motor vehicle it is to be assumed that there is an internal combustion engine as a first drive, with an associated first drive control unit for transmitting control signals to the internal combustion engine, and that there is an electric drive as the second drive, having an associated second drive control unit for transmitting control signals to the electric drive. A control unit is configured as a master control unit and receives presettings relating to a torque which is to be applied jointly by the drives, wherein it is the object of the control unit to implement these presettings by virtue of torque being assigned to the individual drives and corresponding request signals being transmitted to at least one of these drive control units.
In a motor vehicle there is typically also an immobilizer control unit whose task is to check whether a predetermined condition is met, before the motor vehicle can drive away. The predetermined condition includes, for example, the fact that a motor vehicle key is inserted and turned or a specific electronic identifier is read out. So that the individual control units cannot output control signals without the predetermined condition being satisfied, the immobilizer control unit transmits an enable signal to the control devices, typically in response to an interrogation. The intention here is to provide that at least the master control unit and at least one predetermined drive control unit, other than the master control unit, outputs only control signals if the immobilizer control unit has transmitted an enable signal to them after a respective interrogation by them.
Since, of course, the master control unit receives the presettings relating to a torque which is to be applied jointly by the drives, the master control unit is typically the first control unit which transmits an interrogation to the immobilizer control unit. If the master control unit receives the enable, this does not yet mean that the at least one predetermined further drive control unit receives an enable signal to the same extent. It is therefore the case that the master control unit firstly transmits the interrogation, then receives the enable signal and then outputs request signals to the at least one predetermined drive control unit. The latter cannot implement these request signals then but must instead firstly itself transmit an interrogation to the immobilizer control unit, and have received an interrogation signal in response thereto before the implementation can begin. This is disadvantageous because overall too much time passes until the torque request of a vehicle driver is implemented. The same applies if a torque request is output by a control unit, for example an adaptive cruise control system for controlling the distance of the vehicle from a vehicle traveling ahead when the vehicle is being automatically controlled.